THURSDAY, May 19 (HealthDay News) -- The need for a good sense of smell helped lead to the development of large brains in humans and other mammals, scientists suggest.

Another driving force in mammal brain evolution may have been the ability to sense touch through fur, a sense that's acutely developed in mammals.

A team of American paleontologists used high-resolution CT scans to study 190-million-year-old fossil skulls of two of the earliest known mammal species, Morganucodon and Hadrocodium. The results showed that the tiny creatures had much larger-than-expected brains.

"Our new study shows clearly that the olfactory part of the brain and the part of the brain linked to tactile sensation through fur were enlarged in these early mammals," Zhe-Xi Luo, of the Carnegie Museum of Natural History in Pittsburgh, said in a museum news release. "A sophisticated sense of smell and touch would have been crucial for mammals to survive and even thrive in the earliest part of our evolutionary history."

The study was published May 19 in the journal Science.

"Our mammal ancestors didn't develop that larger brain for contemplation, but for the sense of smell and touch. But thanks to these evolutionary advancements, which gave mammals a head start toward developing a large brain, humans some 190 million years later can ponder these very questions of natural history and evolution," Luo said.

More information

The Social Issues Research Centre in the U.K. has more about the sense of smell.